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Thread: Propane Heater Advice

  1. #1

    Default Propane Heater Advice

    I am thinking about installing a large propane heater in our weekend only cabin. We currently have a small direct vent heater in a back bedroom but use it only when we are there. When it is cold, it takes the wood stove half a day to get the temperature to the point where it is somewhat comfortable.

    Empire has a vent free heater that would be great since I would put it in the middle of the cabin and not have to worry about drilling holes in the logs. I can't get comforable with the idea of not venting a propane heater, however. Our cabin is a 1 1/2 story 20' x 30' and it isn't super tight but I am still leary about the thought of going to sleep at night with something like this running. Does anyone have an experience with these heaters?

    Has anyone ever heard of a heater that will vent down through the floor? I would much rather drill a large hole in the floor than through 8" logs and it would fit better in the middle of the room.

    The third option is to install a properly sized direct vent heater and put a low temp thermostat in it and keep it running at +/- 35 degree all the time. Any idea how much propane an 18,000 BTU heater would run through per week doing this?

    Thanks for the feedback.
    JAM

  2. #2
    Member AKDoug's Avatar
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    Default

    I would think that an 18,000 BTU heater is going to run full tilt for the whole day at winter temps to keep a cabin that size and description warm. You are looking at almost 5 gallons a day to heat it.
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    A 20'x30' cabin is way too big for a 18,000 btu heater. You don't want to vent inside, it will make everything wet. Burning that amount of propane generates alot of H20 and CO2. Every molecule of propane burned generates 4 molecules of water and 3 molecules of CO2. I have never heard of a down vent. Hot gas rises.
    Sounds like you need a bigger wood stove.

  4. #4
    Member AKDoug's Avatar
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    When my dad's place was a cabin about the size of yours we went to a big wood stove and a big supply of dry spruce. Took two hours to bring up the heat in the place vs. 6 with birch.
    Bunny Boots and Bearcats: Utility Sled Mayhem

  5. #5

    Default

    Quote Originally Posted by akjam View Post
    I am thinking about installing a large propane heater in our weekend only cabin. We currently have a small direct vent heater in a back bedroom but use it only when we are there. When it is cold, it takes the wood stove half a day to get the temperature to the point where it is somewhat comfortable.

    Empire has a vent free heater that would be great since I would put it in the middle of the cabin and not have to worry about drilling holes in the logs. I can't get comforable with the idea of not venting a propane heater, however. Our cabin is a 1 1/2 story 20' x 30' and it isn't super tight but I am still leary about the thought of going to sleep at night with something like this running. Does anyone have an experience with these heaters?

    Has anyone ever heard of a heater that will vent down through the floor? I would much rather drill a large hole in the floor than through 8" logs and it would fit better in the middle of the room.

    The third option is to install a properly sized direct vent heater and put a low temp thermostat in it and keep it running at +/- 35 degree all the time. Any idea how much propane an 18,000 BTU heater would run through per week doing this?

    Thanks for the feedback.
    JAM
    Hello:
    I live in a 12'x24' cabin that also is not super air tight, but is well insulated, I say not super air tight because I leave a 1.5 foot long crack in the seal around the door like it is for some fresh air at all times. before I had a wood stove I heated exclusively with one of the Mr Heater units that fit on the top of a 20/30/40 pound propane tank, I like the mr heater brand over some others because it didn't use a rubber hose, which I do not trust inside! Mine was 5000/10,000/15,000 btu's and 15,000 would roast you out! You might try one of them to use while your wood stove is warming itself up, then rely on the wood, by doing that a bottle of propane would last quite a while. They also have a low oxygen shut off built in IIRC. worked great for me, something to consider.
    Good luck.

  6. #6
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    Default My propane Experience

    At our cabin (20'x20' with 10' walls and 3/4 loft) I've got one of those wall mounted non-vented 30,000 BTU propane units that they sell at Nothern Tool, and also acasionally at AIH. But Ive also got a wood stove installed in our cabin. We use the wood stove primarily, but rely on the propane to assist in initial temperature raising, as well as maintaining livable temps at night so you dont have to get up to stoke the fire.

    So far it has worked great, yes they do have a low oxygen sensor shut off, but I also errored on the side of caution and installed a CO detector that we use whenever we are at the cabin. No alarms to date. Also as far as moisture problems I havn't noticed an abundance of moisture as there is so little moisture in the air in the winter and the wood stove draws alot of air out the cabin anyway. I do have a problem with the cheap propane regulator at the tank freezing, am replacing it as we speak.

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    Default Here's a little secret

    AKJam,

    I'm going to share a little trade secret. To calculate for the amount of BTU's needed to properly heat your cabin, take the total cubic feet of space ( length x width x height ). Multiply this by a factor of 7 ( i.e. 7 btu per cu. ft ). Example:
    12x20 cabin with steep roof, so estimate an average ceiling hieght of 10ft.
    12x20x10 = 2400 cu. ft. 2400 x 7 = 16,800.
    thus- somewhere around 20,000 BTU unit would suffice.

    I recommend this over some of the rules you may have heard that are based on btu's -per- sq. ft because the square foot rule deals with a 2-dimension space, and we live in a 3-dimension space. We are trying to heat a VOLUME of space, not a flat suface area alone.

    Now- having shared this with everyone, keep in mind that this is a rough, ball-park, rule-of-thumb, quick calculation, and by no means represents something that could be used in place of a proper detailed Heat-Loss Calculation.

    If you live in a colder area such as Fairbanks, the Copper Basin, or the Northern reaches of Alaska, you might want to use a multiplier factor of 8. This quick estimating rule takes into account standard building practice of older 2x4 construction with R8-R11 insulation in the walls. With todays tighter and better built homes ( minimum 2x6 & R19 ) these factors will oversize a heating unit for a typical home. BUT- a cabin is not a typical home, and I share this because most times durint the winter we arrive at our cabins at very cold temps, and we want a bit excess capacity to bring the heat up faster, but don't want the unit so oversized that it short-cycles when the temperature comes up to comfort level.

    Also: vent-free units are typically safe, but I would never recommend them for anything other than temporary heat. Just a personal bias. I would recommend people vent thier permanent installed fuel-fired appliances directly to the outdoors.

  8. #8

    Default CO death in Willow cabin due to inadequate ventilation

    http://www.adn.com/news/alaska/matsu/story/672199.html

    Sad story today in Anchorage Daily News (link above).

    So just how much ventilation IS needed if you run a propane stove inside a cabin (like a Mr. Heater Big Buddy using one-pound propane cylinders). Is cracking several windows about half an inch going to provide enough ventilation to prevent carbon monoxide build-up?

  9. #9
    Member wldboar's Avatar
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    Default

    Quote Originally Posted by northbird1 View Post
    http://www.adn.com/news/alaska/matsu/story/672199.html

    Sad story today in Anchorage Daily News (link above).

    So just how much ventilation IS needed if you run a propane stove inside a cabin (like a Mr. Heater Big Buddy using one-pound propane cylinders). Is cracking several windows about half an inch going to provide enough ventilation to prevent carbon monoxide build-up?

    I was wondering the same thing. We have a travel trailer on property and where gonna use a mr. buddy heater and crack some windows. Don't know now. One good thing is that we do have a fire alarm/co detector. So I guess if it got to bad the thing would go off. Just having some reservations now that I read that story
    The only thing worse than a Subaru is the as*hole who drives it.

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    Keep in mind that carbon monoxide can be at any elevation in a room, could be laying just
    above the floor, or just as easily at ceiling height. Please be careful when using any non-
    vented heating device.

  11. #11
    Member Queen of Kings's Avatar
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    Default I have

    a 12 x 20 2 story cabin and have used a 30,000 through the wall vent for 18 years now. Works great. 1 100 pounder will last easily 3 weekends. Most of my propane is used to heat up the place first. When I get the chance to stay there for 7-10 days at a time it last much longer. Would I change any thing? Nope. When it is really cold -20 or below I some times use a kerosene heater to help the initial warm up time.
    2003 220 Hewescraft Sea Runner 115 Yam'y, Soft Top "Schmidt Happens"

  12. #12
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    Default How much ventilation is safe?

    Typical code requirements call for a minimum equivant free area of 1 sq. inch per every 1000 btu for combustion air. It's important to keep in mind what "equivelant free area" represents. A wall louver or grill that is 10" x 8" doesn't necessarily have 80sq. inches of "free area", because the fins of the stamped or inserted grill face take up space across the face of the grill and displace the total available volume. Thus a 10x8 grill ( 80sq in ) may actually have only 50 sq. in. of free area.

    You can use this as a guide as to how much free area of space you have represented by the open spaces of your windows, doors, outside air access ducts, etc.

    The main point about vent-free units is that they are convenient; but in an enclosed stucture, we typically want to keep the heat inside, and opening up doors or cracking windows lets heat escape. While this is a wise compromise in order to maintain a safe living invironment within the heated structure when using vent-free heaters, you can see why a "direct-vent" appliance is such a benefit. Utilizing vent-free portable heaters such a Mr. Buddy and Big Buddy is fine for short periods of time within confined spaces. After awhile however, new, fresh air ( O2 ) will be required to asure complete combustion of the fuel and prevent the possibilty of CO output. They do have a safety device ( Oxygen Depletion Sensor )-- which is really nothing more than a Thermocouple-type safety circuit, and personally I wouldn't be willing to trust my life with these for any long, continious, period of time.

    Mr. "Schmitt Happens'" 30MBH thru-the-wall heater is most likely a "direct-vent" unit ( Williams, Perfection, Empire, Warmway brand )--- it takes both combustion air from the outside, and expells exhaust gases to the outside, and thereby " isolates" itself from the living area of the structure. This passive type of direct-vent system is typically about a 65% combustion efficiency--- certainly not the highest efficiency that is out there; but what is so nifty about these units is that they are Millivolt gas systems, don't require an electrical power feed, and simply need a gas supply to run. And can be controlled by a wall thermostat that is rated for millivolt systems (automatic heat that doesn't have to be manually manipulated on a continual basis). A pretty handly tradeoff for most Cabin owners.

    Of the vaporizing oil heaters that are wall-mount, direct-vent capable ( Toyo, Monitor & such ) -- these require electricity to power thier low-voltage control boards and line-volt circulation fans. They are very popular up here for good reason, but they don't operate "off the grid ".
    A small generator can run them, however.

  13. #13

    Default I just re-read this post and.............

    It dawned on me, if your wood stove takes half a day to heat the place, the solution is not adding a propane or any other type heater, the solution is a larger or better working wood stove. Why waste money on propane?
    I now heat with wood, with the tiniest stove that i'm aware of, it's an Uncle-Josh brand barely bigger than 2 shoe boxes stacked 1 on the other, the new name for them is NU-WAY stoves, That is my only heat source and at -40 it is sometimes necessary to open the door to let some heat out if I put too much wood in! This is my 5th year heating with it and it uses 1 cord of wood a year, and I live here 365 a year, with at least 6-7 months feeding the stove.
    I'm not suggesting you use something that small only letting you know what a wood stove should do. If I came inside and the place was -10 degrees I could have it 70+ in an hour. Thats a 12'x24' cabin.

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    Smile Propane Heater Advice

    I have a 10 x 12 cabin that I heat with a Buddy Heater. I do not sleep with it on. Want to put in a direct vent Ranaii. The Buddy Heater does build up alot of condensation on the windows. Also have a Co2/ smoke detector. I do not want to run the generator for heat but the direct vent is the only way to go. My 2 cents.

  15. #15
    Member Hunt'N'Photos's Avatar
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    Default My heat solution

    AKJam,
    I have a 16x24 cabin with a Blaze King princess stove and an Empire "direct-vent" 25,000 btu propane heater. With that combination I can get the chill out of the cabin in 15-20 minutes and get it comfortable in the worst cold in 1-2 hours. Once its comfortable I turn the propane furnace down to about 55 and use just wood during the day. When the blaze king dyes out at night the propane kicks in and keeps it at a comfortable temp for sleeping. Works very well like that and so far I have not gone through a 100# propane bottle in a year and a half using the cabin for weekends 1-3 times per month. No problems with moisture and no worries about CO2 with that setup. Let me know if you have any questions.
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